Need the Release notes for Alfresco-4.0

Dear friends,I am implementing an Alfresco solution, and heard about Alfresco-4.0 arrival, i would like to use it, since it should contain less bugs, but i need it's releases notes to decide whether it's better for me to upgrade or not!

I have noticed that the jBPM work-flows aren't used anymore?! have they been deprecated or Activities is a better solution?!

i need the release notes, in addition to your advices if you have good experience in the versions of Alfresco.